Used instead of belly when speaking in a form of internet slang (old mans tavern talk). Usually associated with the word ma (instead of my) and happi (instead of happy) to represent ones belleh being happi when he/she's eaten something tastay.

Ma belleh were r8 hapi last naight when i haz had a curry mh om nom nom nom nom.

Beef steak pie and chips, two desserts and two waffles...mmm... ma belleh is happi.

The night me, Joe and Stu went to the Hog's head and we had 1 and 1/3 meals each, and a desert!
Mmm... ma belleh was happi that night. : )